The Flow Cytometry'/Fluorescence Imaging Shared Resource provides Cancer Center investigators with advanced instrumentation for the study of cells. To this end, it aims to provide state-of-the-art flow cytometers and image analysis systems for acquisition of data; to provide computer hardware and software for the analysis of cellular data derived from these instruments; to train scientists in use of the instruments and software; to develop and implement new techniques for cell analysis; and to encourage communication among scientists on methods of common interest. For flow cytometry, the Shared Resource has two Becton Dickinson instruments: a FACStar Plus VIS/UV seven-parameter cytometer with TurboSort upgrade for sorting and advanced applications and a FACScan five-parameter cytometer for routine analysis. The Resource laboratory also has three image analysis systems: a Bio-Rad MRC-1024 krypton/argon laser confocal system; a Meridian Ultima UV/VIS argon laser confocal system; and a Zeiss Axiophot photomicroscope with a cooled CCD detector. There are, within the Shared Resource, a Silicon Graphics workstation, three networked Macintosh workstations, and a Codonics dye~sublimation printer for publication-quality color printing. During FY 96-97, the Flow Cytometry/'Fluorescence Imaging Shared Resource was used by approximately 100 different individuals from the labs of 34 investigators. For that period, 2,741 out of a total of 2,858 billed hours of use were by Cancer Center members (95.9% of total billed use). At the present time, Cancer Center investigators using the Shared Resource hold active grants totalling $10,399,757 in annual direct costs. Of this sum, 97% is from peer-reviewed grants (84.2% from NIH).